This is a revised application for a Ruth L. Kirschstein Institutional National Research Service Award (NRSA/T32) developed for post-doctoral research training for MD, MD/PhD, and PhD fellows preparing for a career as an independent investigator in translational pediatric pathology research. There is a particular focus on research into the pathophysiology of disorders of the heart, lung or blood that are particularly prevalent i children. The Program proposal includes formal didactic training in translational medicine, human subjects research, the ethical conduct of research, and innovative technologies such as genomics and proteomics as well as a mentored research experience in an academically rich environment that is supported by numerous educational and career development resources provided by Children's Hospital Boston and the Harvard Catalyst Clinical Translational Sciences Center (CTSC). The Training Program centers around the Department of Pathology at Children's Hospital Boston and involves its research faculty supported by a select group of translational investigators from other Departments at Children's Hospital Boston, the Brigham and Women's Hospital, Harvard Medical School, and the Broad Institute. To enhance the collaborative, translational pathology nature of the Program, trainees are also required to draw upon the experience of the clinical pediatric pathology faculty and are encouraged to utilize the substantial frozen and formalin-fixed, paraffin-embedded tissue resources of the Department for their studies. Above all, the overriding goal of the Program is to endow the next generation of translational pediatric pathologists with the skills to contribute to innovative diagnostics and treatment of pediatric diseases.